Libplot has its own versioning scheme, independent of the scheme used for
numbering the releases of the plotutils package.  The version of libplot in
this directory is 4.4, age=2.  That means

	interface number = 4
	revision = 4
	
	Support for interfaces extending backward by 2 unit from current
	interface number, i.e., support for the interfaces supplied by
	libplot 2.x and libplot 3.x.

The libplot 1.x interface is not supported, because its function names did
not use the "pl_" prefix.  However, if you add a `#include <plotcompat.h>'
directive to code written for libplot 1.x or for the ancient pre-GNU (Unix)
libplot, it should be possible to link it with the current version.
